Gas-liquid separation device for fluidized bed reactor

Abstract

A gas-liquid separator suitable for separating liquid and gas in an ebullated bed reactor under operating conditions is disclosed. The apparatus may be used in the petroleum and chemical processing industry to catalytically react a hydrocarbonaceous feedstock in the presence of hydrogen at elevated temperature and pressure to separate gas and liquid from a gas and liquid mixture within the reactor. The device is generally vertically oriented and can be mounted in the flow-through tray of an ebullated bed reactor. The apparatus comprises: a transfer conduit for transferring a gas-liquid mixture stream from a lower section of an ebullated bed reactor to an upper section of the reactor; a vortex separation section having a rich gas flow outlet and a rich liquid flow outlet; and a rich gas flow outlet conduit located on top of the vortex separation section and adjacent to the vortex separation section. The delivery conduit includes internal means, such as a helical or helical insert, for generating a helical flow in the gas-liquid mixture. The vortex separation section is located at the top of the transfer conduit and includes separation means for separating the gas-liquid mixture stream into a rich liquid stream and a rich gas stream. A separator conduit extending from the top of the vortex separation section to an upper opening of the transfer conduit may be used as the separation device, the separator conduit aligned with the rich gas flow outlet and having substantially the same cross-sectional dimension as the rich gas flow outlet. Benefits provided include increasing the efficiency of gas and liquid separation and reducing the gas content within the reactor.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of priority to U.S. Provisional Patent Application Serial No. 63 / 426,031, filed on November 16, 2022, entitled "GAS - LIQUID SEPARATION DEVICE FOR AN EBULLATED BED REACTOR", the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] Disclosed is a gas - liquid separator for an ebullated bed hydrotreating reactor. The separator can be used in the petroleum and chemical processing industries to catalytically react hydrocarbon - containing feeds in the presence of hydrogen at high temperatures and pressures to separate gases and liquids from gas - liquid mixtures. Background Art

[0004] Ebullated bed (EB) reactor hydrotreating involves flowing a liquid or a slurry of liquid, solid, and gas simultaneously through a vertical cylindrical vessel containing catalyst. The catalyst moves randomly in the liquid, and the overall volume of the catalyst dispersed in the liquid medium is greater than its volume when at rest. EB technology has found commercial applications in the upgrading of heavy liquid hydrocarbons or the conversion of coal to synthetic fuels. The method is described in detail in U.S. Patent No. 25,770 to Johanson. Several other patent publications describe EB reactors and methods, as well as useful modifications, such as U.S. Patent Nos. 4,221,653, 4,151,073, 4,354,852, 3,668,116, 4,012,314, 4,886,644, 5,066,467, 5,624,642, and 7,060,228. Generally, a mixture of hydrocarbon liquid and hydrogen is conveyed upward at a certain rate through a bed of catalyst particles such that the particles are forced to move randomly as the liquid and gas flow upward through the bed. The movement of the catalyst bed is controlled by a recycle liquid flow such that, in the steady state, most of the catalyst does not rise above a defined level in the reactor. Vapor is conveyed with the liquid through the upper layer of catalyst particles into a catalyst - free zone and removed in the upper part of the reactor.

[0005] In a fluidized bed during operation, a large amount of hydrogen and light hydrocarbon vapors rise through the reaction zone to the catalyst-free zone. The liquid is both recycled to the bottom of the reactor and removed from the reactor as a product from this catalyst-free zone. The vapor is separated from the liquid recycle stream before being conveyed through a recycle conduit to the suction inlet of the recycle pump. The recycle pump (fluidizing pump) maintains the expansion (fluidization) and random movement of the catalyst particles at a constant and stable level. The gas or vapor present in the recycled liquid significantly reduces the capacity of the recycle pump, as well as the residence time of the liquid in the reactor, and limits the hydrogen partial pressure.

[0006] The reactor design employed in a catalytic hydrogenation process with a fluidized bed of catalyst particles has a central vertical recycle conduit downcomer to recycle the liquid from the catalyst-free zone above the fluidized catalyst bed to the suction inlet of the recycle pump to recycle the liquid through the catalytic reaction zone. The liquid recycle in the upper part of the reactor is used to fluidize the catalyst bed, maintain temperature uniformity throughout the reactor, and stabilize the catalyst bed.

[0007] The EB reactor process may encounter several technical operation challenges. For example, if hydrogen and other gases are not substantially removed from the liquid recycle stream by the recycle pump, the recycle gas may reduce the conversion rate by occupying the reactor volume that would otherwise be occupied by the liquid feedstock. Therefore, hydrogen and other gases must be separated from the recycled liquid before being reintroduced into the three-phase gas / liquid / catalyst reaction zone. Since the catalyst in the three-phase zone is mainly fluidized by the upward flowing liquid stream, a recycle stream with a high gas content will reduce the liquid velocity in the three-phase zone. Therefore, the recycle pump needs to operate at a higher rotational speed to maintain a constant height of the expanded catalyst bed. If the maximum pump speed is reached, the momentum of the upward flowing liquid will be insufficient to suspend the catalyst, which may cause the catalyst to settle on the support grid. Then hot spots may form in the settled catalyst bed, leading to safety problems.

[0008] Therefore, there is a continuing need to improve the operation and design of fluidized bed reactors, including improving gas and liquid separation in fluidized bed reactors. SUMMARY OF THE INVENTION

[0009] The present invention relates to a gas-liquid separation device (also referred to herein as a "separator") suitable for separating gases and liquids in a fluidized bed reactor under operating conditions. The device provides effective separation of the gas and liquid in the gas-liquid mixture when installed in the circulation tray of the fluidized bed reactor. The device provides effective separation of the gas and liquid while minimizing the gas holdup in the reactor. The device is well-suited for retrofit applications and can be used in new reactor designs to achieve efficient gas and liquid separation, thereby improving the operating performance of the fluidized bed reactor. The benefits provided include increased efficiency of gas and liquid separation and reduced gas holdup within the reactor. While the device is generally intended for use in fluidized bed reactors, it can also be used in other petroleum and chemical processing operations.

[0010] The gas-liquid separator device is typically vertically oriented within the reactor and may generally be installed in the circulation (recirculation) tray of the fluidized bed reactor. The device includes: a transfer conduit for transferring the gas-liquid mixture stream from the lower section of the fluidized bed reactor to the upper section of the reactor; a vortex separation section having a gas-rich stream outlet, a liquid-rich stream outlet, and a top plate; and a gas-rich stream outlet conduit located at the top of the vortex separation section and adjacent to the vortex separation section. The transfer conduit includes internal means for generating a helical flow in the gas-liquid mixture, such as a helical or spiral insert. The vortex separation section is located at the top of the transfer conduit and includes separation means for separating the gas-liquid mixture stream into a liquid-rich stream and a gas-rich stream. A separator conduit extending from the top of the vortex separation section to the upper opening of the transfer conduit can serve as the separation means, the separator conduit being aligned with the gas-rich stream outlet and having a cross-sectional dimension substantially the same as the gas-rich stream outlet.

[0011] The present invention also relates to a method for separating gases and liquids in a gas-liquid mixture. The method generally includes vertically conveying the gas-liquid mixture through a conduit having internal means to generate a vertical helical flow in the gas-liquid mixture flowing through the conduit. The helical flow gas-liquid mixture is then fed into a vortex separation section such that the helical flow gas-liquid mixture contacts a separator conduit. The separator conduit is aligned substantially parallel to the vertical flow path of the helical flow gas-liquid mixture along its length. The helical flow of the mixture causes the liquid to be primarily located on the outside of the helical flow path, while the inside of the helix is primarily gas. The separator conduit provides separation of the liquid-rich stream flowing outside the separator conduit from the gas-rich stream flowing inside the separator conduit. The liquid-rich stream is then conveyed to the liquid-rich stream outlet, and the gas-rich stream is conveyed to a separate gas-rich stream outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figures 1 to 3A representative view of a gas-liquid separation device according to an embodiment of the present invention and its installation in a fluidized bed reactor is provided. The scope of the present invention is not limited by these representative drawings and should be understood to be defined by the appended claims.

[0013] Figure 1 A side cross-sectional view of the separation device of the present invention is depicted.

[0014] Figure 2 An isometric side view of the separation device of the present invention is depicted.

[0015] Figure 3 A top section of a fluidized bed reactor with a plurality of separation devices installed on a circulation (recirculation) tray according to the present invention is depicted. Detailed Description

[0016] It will be apparent from the detailed description provided herein what the specific embodiments and benefits are. However, it should be understood that the detailed description, the drawings, and any specific examples, while indicating advantageous embodiments (including some preferred embodiments), are intended for illustrative purposes only and are not intended to limit the scope of the present invention.

[0017] The present invention generally relates to a separation device (“separator”) for separating gas and liquid from a gas-liquid mixture. The separator is particularly suitable for hydrotreating reactors, especially fluidized bed reactors. When installed in a circulation (recirculation) tray of a fluidized bed reactor, the device provides effective separation of gas and liquid in the gas-liquid mixture while minimizing the gas holdup in the reactor.

[0018] The separator includes: a transfer conduit; a vortex separation section having a separator conduit located therein, a gas outlet, and a liquid outlet; and a gas conduit for conveying gas from the separator to the exterior of the device. The transfer conduit includes internal means for generating a helical flow in the gas-liquid mixture, such as a helical or spiral insert. The vortex separation section is located at the top of the transfer conduit and includes a separation device for separating the gas-liquid mixture stream into a liquid-rich stream and a gas-rich stream. The separator conduit extending from the top of the vortex separation section to the upper opening of the transfer conduit can serve as the separation device, which is aligned with the gas-rich stream outlet and has a cross-sectional dimension substantially the same as that of the gas-rich stream outlet. The gas-rich stream outlet conduit is used to convey the gas-rich stream to the exterior of the device.

[0019] As long as the gas-liquid mixture flows vertically upward in the conduit, the transfer conduit can generally have any cross-sectional shape. Conveniently available conduit shapes (such as reactor-grade pipes) are suitable and are preferably designed to allow a suitable gas-liquid mixture flow rate and a minimum pressure drop. The typical pipe diameter sizes that can be used range from about 2 inches to 8 inches, or 4 inches to 6 inches, or a diameter of about 5 inches. The transfer conduit can include a lower section and an upper section, the lower section and the upper section being open at both ends and configured to mate together at the corresponding ends to form the conduit. In such cases, the upper section can include internal means to generate a helical flow in the gas-liquid mixture flowing through the conduit, while the lower section is configured to allow the gas-liquid mixture to flow into the lower opening and be conveyed through the lower section into the lower end of the upper section of the conduit. Generally, the internal means for generating a helical flow in the liquid and gas mixture can be a helix or helical insert having a length substantially the same as the length of the upper section of the transfer conduit, where the insert is positioned within the upper section of the transfer conduit from the top to the bottom and has dimensions substantially the same as the internal cross-section of the transfer conduit. Other structures or inserts for generating a helical gas-liquid flow through the transfer conduit can also be used. When the separator is installed in the flow-through tray of a fluidized bed reactor, the lower section of the transfer conduit will generally be adapted to fit into the corresponding opening in the flow-through tray such that the gas-liquid mixture can be conveyed from the lower section of the reactor to the separation means.

[0020] The vortex separation section is open at the bottom and has a larger cross-sectional area and dimensions than the transfer conduit such that it can fit over the upper portion of the transfer conduit. To this end, the vortex separation section can be positioned above the top (upper section) of the transfer conduit to extend below the top of the transfer conduit. Generally, the vortex separation section is sized to provide a liquid flow path between the outside of the transfer conduit and the overlapping interior of the vortex separation section. When installed in the flow-through tray of a fluidized bed reactor, a separator having a circular vortex separation section and a transfer conduit creates an annular liquid flow path between the outside of the transfer conduit and the interior of the separation section. The vortex separation section can generally be substantially circular or a pipe section having a diameter in the range of about 4 inches to 12 inches, or 6 inches to 10 inches, or 6 inches to 9 inches, or 7 inches to 9 inches, or having a diameter of about 8 inches. The term "substantially" herein is intended to mean any normal dimensional variations that would be expected by one of ordinary skill in the art.

[0021] Internal separation devices for separating gas-liquid mixtures into rich liquid and rich gas streams within a vortex separation section typically utilize the separation of liquid and gas generated within the vortex to separate the two phases into rich liquid and rich gas streams. Each stream is directed to a corresponding rich gas or rich liquid stream outlet. In some cases, the rich gas stream outlet may be located at the top of the vortex separation section. For example, the outlet may be an opening in the top plate. The internal separation device may then include, for example, a separator conduit extending from the top of the vortex separation section to the upper opening of the transfer conduit. In such cases, the separator conduit may be aligned with the rich gas stream outlet present in the top plate and have a cross-sectional dimension substantially the same as the rich gas stream outlet.

[0022] There is also a top plate on the vortex separation section. In the case where the rich gas stream flows vertically through the top of the vortex separation section, the top plate will have a rich gas stream outlet sized to allow the flow rate of the rich gas stream to be transferred from the vortex separation section into the rich gas stream outlet conduit. A separation device (such as a conduit or pipe section) will typically be aligned with the rich gas stream outlet in the top plate to allow the gas separated within the vortex separation section to flow into the rich gas stream outlet conduit. The rich gas stream outlet and conduit serving as the separation device will generally have substantially the same cross-sectional dimension or, in the case of a pipe, the same diameter. The cross-sectional area and size of the separator conduit are typically smaller than the cross-sectional area and size of the transfer conduit. The internal separation device can generally be substantially circular or a pipe section having a diameter in the range of about 1 inch to 6 inches, or 1 inch to 4 inches, or 1 inch to 3 inches, or 2 inches to 3 inches, or having a diameter of about 2.5 inches. The term "substantially" herein is intended to represent any normal dimensional variation that would be expected by one of ordinary skill in the art.

[0023] The rich gas stream outlet conduit typically has a larger cross-sectional area or diameter than the separator conduit and a smaller cross-sectional area or diameter than the vortex separation section. The outlet conduit can be inclined to direct the gas flow in a desired direction. In the case of a fluidized bed reactor installation, the outlet conduit can be an elbow, typically oriented at an angle of about 30 degrees to 60 degrees with respect to the horizontal direction. In a circulating disk installation, the outlet flow direction can also be oriented relative to the circumference of the disk. For example, the outlet elbow can be oriented at an angle of about 15 degrees to 60 degrees with respect to the radial orientation of the separation device relative to the reactor center.

[0024] Generally speaking, the transfer conduit, internal helical flow device, vortex separation section, internal separation device, rich gas stream outlet, and rich gas stream outlet conduit can all be centered and aligned around the same vertical axis. In the case of being installed on the circulating disk of a fluidized bed reactor, such an arrangement creates a substantially vertical flow path through the device up to the separation device. The rich gas stream continues to flow vertically upward and exits the device through the rich gas stream outlet conduit. The rich liquid stream turns downward towards the liquid outlet, flows onto the disk, and passes downward through the downcomer.

[0025] When installed in a reactor or used in another application, various support structures can be used to support the separation device. For example, when installed in the flow-through tray of a fluidized bed reactor, the lower section opening of the transfer conduit can be welded or otherwise supported on the flow-through tray, such as by brackets installed within the reactor.

[0026] The present invention also relates to the use of the separation device in any application where it may be necessary to separate gases and liquids from a gas-liquid mixture, as well as to any equipment in which the separation device is installed, such as a flow-through (recirculation) tray or a fluidized bed reactor.

[0027] The present invention also relates to a method for separating gases and liquids from a gas-liquid mixture. The method generally includes: vertically conveying the gas-liquid mixture through a conduit having internal means to create a vertical spiral flow in the vertically flowing gas-liquid mixture through the conduit; conveying the spiral flow gas-liquid mixture into a vortex separation section, where the spiral flow gas-liquid mixture contacts a separator conduit that is aligned substantially parallel to the vertical flow path of the spiral flow gas-liquid mixture along its length, thereby forming a liquid-rich flow on the outside of the separator conduit and a gas-rich flow on the inside of the separator conduit; and conveying the liquid-rich flow to a liquid-rich flow outlet and the gas-rich flow to a separate gas-rich flow outlet. The method can be used with one or more separators described herein to separate gases and liquids from a gas-liquid mixture, particularly in flow-through tray and fluidized bed reactor applications.

[0028] In an embodiment of the present invention, as Figures 1 to 3 shown, the separation device can have a cross-sectional view as Figure 1 shown. The transfer conduit can include a lower section 10 of the transfer conduit, an upper section 20 of the transfer conduit, and a connection 25 between the lower and upper sections. The transfer conduit includes a lower opening outlet 30 and an upper opening outlet 40. An internal separation device, such as a spiral insert 50, is shown in the upper section. A vortex separation section 60 is shown to include an internal separator conduit 70, a top plate 75, a liquid-rich flow outlet 80, and a gas-rich flow outlet 90. The gas-rich flow outlet conduit 100 is shown to have an angular orientation of approximately 45 degrees relative to the horizontal direction, and the outlet elbow orientation is approximately 30 degrees relative to the radial orientation of the separation device relative to the center of the reactor.

[0029] Figure 2 An isometric view of the outside of the separation device is shown. As shown, the separation device includes the Figure 1 same transfer conduit configuration, including a lower section 10 of the transfer conduit, an upper section 20 of the transfer conduit, and a connection 25 between the upper and lower sections. For ease of illustration, Figure 2It also includes a vortex separation section 60, a top plate 75, a rich liquid outlet opening 80 (in an annular region between the vortex separation section and the exterior of the transfer conduit), and a rich gas flow outlet conduit 100. Although Figure 1 and Figure 2 illustrate one embodiment of a possible apparatus configuration, other configurations may also be used.

[0030] Figure 3 An embodiment of the present invention is illustrated, in which a plurality of separation devices 110 are mounted in a flow-through tray 120 in the top section of a ebullated bed reactor 130. Also shown are a downcomer 140 and a reactor effluent outlet 150.

[0031] The separation devices of the present invention and their associated aspects, including the specific embodiments described herein, provide certain benefits and improvements in hydrotreating applications, including improved gas-liquid separation and reduced gas entrainment in the downcomer liquid flow in an ebullated bed installation.

[0032] The foregoing description of one or more embodiments of the invention is primarily for purposes of illustration, and it should be recognized that many variations may still be made that still incorporate the essence of the invention. When determining the scope of the invention, reference should be made to the appended claims.

[0033] All patents and publications cited in the above description of the invention are hereby incorporated herein by reference.

Claims

1. A gas-liquid separator adapted to separate liquid and gas in a fluidized bed reactor under operating conditions, the separating device comprising: A transfer conduit for transferring a gas-liquid mixture stream from a lower section of the fluidized bed reactor to an upper section of the reactor, wherein the conduit is vertically oriented during operation in the reactor, the conduit having a lower opening and an upper opening and including internal means for generating a helical flow in the liquid and gas mixture flowing vertically through the conduit; A vortex separation section located at the top of the transfer conduit and adjacent to the upper opening of the transfer conduit, the vortex separation section including internal separation means for separating the gas-liquid mixture stream into a liquid-rich stream and a gas-rich stream, a top plate, an outlet for the liquid-rich stream and an outlet for the gas-rich stream; and A gas-rich stream outlet conduit located at the top of the vortex separation section and adjacent to the vortex separation section and in fluid communication with the gas-rich stream outlet of the vortex separation section.

2. The separator according to claim 1, wherein the transfer conduit comprises a lower section and an upper section, the lower section and the upper section being open at both ends and configured to fit together at corresponding ends to form the conduit, the upper section including the internal means for generating a helical flow in the gas-liquid mixture flowing through the conduit, while the lower section is configured to allow the gas-liquid mixture to flow into the lower opening and be transferred through the lower section into the lower end of the upper section of the conduit.

3. The separator according to claim 2, wherein the lower section of the transfer conduit is adapted to fit into a corresponding opening in a flow-through tray of the fluidized bed reactor such that the gas-liquid mixture can be transferred from the lower section of the reactor to the separating device.

4. The separator according to any one of claims 2 to 3, wherein the upper section and the lower section of the transfer conduit are substantially circular or are pipe sections, the diameter of the pipe sections being in the range of about 2 inches to 8 inches.

5. The separator according to any one of claims 2 to 4, wherein the internal means for generating a helical flow in the liquid and gas mixture is a helix or helical insert having a length substantially the same as the length of the upper section of the transfer conduit, wherein the insert is positioned within the upper section of the transfer conduit from the top to the bottom thereof and has dimensions substantially the same as the internal cross-section of the transfer conduit.

6. The separator according to any one of claims 1 to 5, wherein the vortex separation section is open at the bottom, has a cross-sectional area and dimensions greater than those of the transfer conduit, is located above the top of the transfer conduit and extends below the top of the transfer conduit.

7. The separator according to claim 6, wherein the vortex separation section is sized to provide a liquid flow path between the outside of the conduit and the inside of the vortex separation section.

8. The separator according to any one of claims 1 to 7, wherein the vortex separation section is substantially circular or is a duct section, and the diameter of the duct section is in the range of about 4 inches to 12 inches.

9. The separator according to claim 7, wherein the rich liquid flow outlet includes the liquid flow path.

10. The separator according to any one of claims 1 to 9, wherein the rich gas flow outlet is located at the top of the vortex separation section.

11. The separator according to any one of claims 1 to 10, wherein the internal separation device includes a separator duct extending from the top of the vortex separation section to the upper opening of the transfer duct, the separator duct being aligned with the rich gas flow outlet and having a cross-sectional dimension substantially the same as that of the rich gas flow outlet.

12. The separator according to any one of claims 1 to 11, wherein the internal separation device includes a separator duct having a smaller cross-sectional area and dimension than that of the transfer duct.

13. The separator according to any one of claims 1 to 12, wherein the internal separation device is substantially circular or is a duct section, and the diameter of the duct section is in the range of about 1 inch to 6 inches.

14. The separator according to any one of claims 1 to 13, wherein the transfer duct, the internal spiral flow device, the vortex separation section, the internal separation device, the rich gas flow outlet, and the rich gas flow outlet duct are centered and aligned about the same vertical axis.

15. A flow-through tray gas-liquid separator for a fluidized bed reactor, comprising a plurality of separators according to any one of claims 1 to 14.

16. A fluidized bed reactor, comprising the flow-through tray gas-liquid separator according to claim 15.

17. A method for separating gas and liquid in a gas-liquid mixture, the method comprising: Vertically conveying a gas-liquid mixture through a duct having internal means to generate a vertical spiral flow in the gas-liquid mixture flowing vertically through the duct; conveying the spiral flow gas-liquid mixture into a vortex separation section, wherein the spiral flow gas-liquid mixture contacts a separator duct that is aligned substantially parallel to the vertical flow path of the spiral flow gas-liquid mixture along its length, thereby forming a rich liquid flow on the outside of the separator duct and a rich gas flow on the inside of the separator duct; and conveying the rich liquid flow to a rich liquid flow outlet and conveying the rich gas flow to a separate rich gas flow outlet.

18. The method according to claim 17, wherein a plurality of separators according to any one of claims 1 to 14 are used to separate the gas and the liquid from the gas-liquid mixture.

19. The method according to claim 18, wherein the method is performed using the flow-through tray gas-liquid separator according to claim 15.

20. The method according to claim 18, wherein the method is performed inside the fluidized bed reactor according to claim 16.

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